The invention relates to a motor vehicle, particularly a passenger car, the underside of which that faces the road, has wheel housings for the front and rear wheels and has an aerodynamically streamlined shape over at least a substantial portion of said underside.
In the case of a known arrangement of the above-mentioned type, disclosed in German Utility Model (DE-GM) No. 80 23 035, the underside of the motor vehicle is developed with a smooth surface with assemblies and parts of the chassis, such as links, axles, or the like, being covered. By means of the smooth-surface development of the underside, the drag coefficient of the vehicle is reduced. However, it is a disadvantage in the case of this arrangement that in the area of the underside of the vehicle, no measures are taken for generating negative lift.
It is an object of the present invention to take such measures at the underside of a motor vehicle that, with a good drag coefficient, negative lift is generated that improves the driving behavior of the motor vehicle.
According to the invention, this object is achieved by providing downwardly open upwardly inclined air inlet ducts leading to the wheel housings, the upper peripheral areas of the inlet ducts being formed by convexly shaped sections.
The main advantages achieved by means of the invention are the fact that by means of the arrangement of inlet ducts in front of the wheel houses having convexly extending upper peripheries, diffuser areas are created at the underside that, seen in longitudinal direction of the vehicle, require little space, so that a relatively large-surface area of the underside can be used for the production of negative lift.
Negative lift is therefore produced only in the areas in front of the inlet ducts, since there the flow velocity is increased resulting in a reduction of pressure. In the wheel houses themselves, no negative lift is generated; they are used only for the discharge of the air to the diffuser areas, a low pressure level existing in the large-volume wheel houses that supports the discharge of air.
As a result of the shaped sections of the upper peripheries that extend convexly to the road, the flow, while utilizing the boundary layer effect, without detachment, rests against the upper peripheries of the inlet ducts. The inlet ducts may selectively be arranged in front of the front wheels or the rear wheels ,but also in front of the front wheels and the rear wheels, according to different preferred embodiments of the invention. By means of the latter arrangement, an optimized negative lift effect is achieved, because through the mounting of inlet ducts in front of the rear wheels, the negative lift effect is additionally improved in the area of the front wheels. In addition, the air flow in the area of the wheel houses can be used for brake cooling. A further improvement of the negative lift effect is achieved by means of the outlet ducts connected to the wheel houses.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.